1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to a system and a method for allocating communication system resources to calls for optimizing network system performance.
2. Description of Related Art
In a typical satellite communications system, caller communication units are linked to ground-based communication facilities, or ground nodes, which, in turn, are linked to satellites. In some cases, individual communication units are linked directly to a satellite. The amount of caller traffic in a communications system is limited by the available communication bandwidth of the system. When caller demand exceeds the capacity of the system, new callers are denied access.
In conventional communication systems, there is a fixed amount of satellite bandwidth assigned to each ground node. The available bandwidth in these systems is often used inefficiently. For example, one ground node may be overloaded with calls, denying access to new callers, whereas a neighboring ground node may be underutilized, leaving unused satellite bandwidth assigned to that ground node. When a ground station becomes overloaded with calls, there is no mechanism in a conventional satellite system for transferring satellite bandwidth from an underutilized ground station.
To overcome this deficiency, demand-assigned multiple access (DAMA) systems utilize a central control station that allocates satellite bandwidth on a call-by-call basis. Such conventional systems employ a simple, greedy strategy for assigning satellite bandwidth. That is, a ground node requests additional bandwidth from the central control station when a new call is received. The central control station assigns satellite bandwidth to the ground nodes as bandwidth requests are received allowing bandwidth to be reassigned from an underutilized ground node to an overloaded one.
Instead of using a greedy approach, a few conventional satellite systems use a predictive approach, whereby the central control station predicts which stations will be receiving a high call demand, and allocates extra bandwidth to those stations in anticipation of their future need.
Nevertheless, conventional greedy DAMA systems and predictive DAMA systems do not always allocate resources in an optimal manner. For example, in a system in which calls have different priority levels, if available bandwidth is allocated for handling a high demand of low priority calls, future higher priority calls may be blocked, or calls in progress may require preempting for satisfying demands of higher priority calls. As another example, if the system allocates all available bandwidth to one ground node for handling a high call demand or a high predicted call demand, there might be a lack of bandwidth available for another ground node that will receive high call demand in the future.
What is needed is a system that measures trade-offs involved in allocating bandwidth between stations over time. Further, what is needed is a system that determines an optimal allocation of communication resources (i.e., bandwidth) that maximizes overall network system performance.